WO2005007786A2

WO2005007786A2 - Dithiocarbamate and borated dithiocarbamate compositions; and lubricating compositions containing same

Info

Publication number: WO2005007786A2
Application number: PCT/US2004/022107
Authority: WO
Inventors: Thomas J. Karol; Liehpao Oscar Farng; Andrew G. Horodysky
Original assignee: R.T. Vanderbilt Company, Inc.
Priority date: 2003-07-10
Filing date: 2004-07-12
Publication date: 2005-01-27
Also published as: WO2005007786A3

Abstract

A dithiocarbamate compound of the formula (I), (II) and (III), wherein for formula (I), R1 and R2 are the same or different and represent alkyl groups, branched or straight chain, having 1 to 13 carbon atoms, R3 and R4 are the same or different and represent hydrogen, boric acid ester residue or mixtures thereof, and wherein for formulas (II) and (III), R1 and R2 are the same or different and represent alkyl groups, branched or straight chain, having 1 to 13 carbons atoms. Also contemplated are dithiocarbamate compounds formed from the reaction of the dithiocarbamate compound of formula (I) where R3 and R4 are hydrogen with boric acid. The dithiocarbamate compounds are used as part of lubricant composition containing a base oil.

Description

DITHIOCA-RB-AMATE AND BORATED DITHIOCARBAMATE COMPOSITIONS; AND LUBRICATING COMPOSITIONS CONTAINING SAME

SPECIFICATION BACKGROUND OF THE INVENTION The invention concerns lubricating compositions having improved properties. Another aspect of the invention relates to additive compositions which impart antioxidant, antiwear and antiscuffing properties to lubricating compositions, and particularly useful for internal combustion engines such as gasoline engine and diesel engine; as they do not contain phosphorous which leads to catalytic converter deactivation. Additives known as antiwear agents are employed to increase the load carrying capacity of lubricants. The antiwear agents promote the formation of a surface film and thereby prevent wear of the contacting surfaces. The mechanical efficiency enhanced by decreased friction loss further results in decreased fuel consumption and energy savings. It is known that certain organic dithiocarbamates possess antiwear properties as well as other desirable lubricating characteristics as disclosed in U.S. Pat. No. 3,139,405. Surprisingly, it has now been discovered that the dithiocarbamates diols as well as the borated diols described herein provide exceptional antiwear performance. This dramatic improvement of the dithiocarbamate is attributed to the extra metal coordination afforded by either the diol presence or the borated diol presence in the molecule.

SUMMARY OF THE INVENTION According to the invention, there are provided compositions comprising dithiocarbamates of the formula

wherein Rl and R2 are the same or different and represent alkyl groups, branched or straight chain, having 1 to 13 carbon atoms, R3 and R4 are the same or different and represent hydrogen, boric acid ester residue or mixtures thereof. Borate esters of diols are believed to exist in many forms that could include the following structures (IT) and (IE) which are presumed to be the most stable of the structures to hydrolysis:

DETAILED DESCRIPTION OF THE INVENTION The invention can be prepared by reacting a secondary amine with carbon disulfide to form a source of dithiocarbamic acid. The acid is then converted to an ester diol by the following schemes:

The product is a borate ester with unreacted dithiocarbamate diol

In the above reaction scheme, n is in the range of about 0.25 to about 2.0, preferably about 0.75 to about 1.25 and more preferably is about 1.0. x is an integer from 1 to 3.

In one embodiment of the invention, when R3 and R4 both represent hydrogen, then Rl and R2 are the same or different and represent alkyl groups, branched or straight chain, having 1 to 7 carbon atoms. In another embodiment of the invention, when R3 and R4 both represent hydrogen, then Rl and R2 are the same or different and represent alkyl groups, branched or straight chain, having 5 or 6 carbon atoms. In a further embodiment of the invention, when R3 and R4 both represent hydrogen, then Rl and R2 are the same and are either n-butyl or n-pentyl. In another embodiment of the invention, when R3 and R4 both represent hydrogen, then Rl and R2 are the same or different and represent alkyl groups, branched or straight chain having 8 or 13 carbons; a preferred embodiment is where Rl and R2 are both 2-ethylhexyl. In another embodiment of the invention, for compounds of structure (IT) or (IH), Rl and R2 are the same or different and represent alkyl groups, branched or straight chain, having 1 to 7 carbon atoms. In another embodiment of the invention, Rl and R2 are the same or different and represent alkyl groups, branched or straight chain, having 5 or 6 carbon atoms, hi a further embodiment of the invention, Rl and R2 are the same and are either n-butyl or n-pentyl. In another embodiment of the invention, Rl and R2 are the same or different and represent alkyl groups, branched or straight chain having 8 or 13 carbons; a preferred embodiment is where Rl and R2 are both 2-ethylhexyl. The base oils employed as lubricant vehicles are typical natural and synthetic oils used in automotive and industrial applications such as, among others, turbine oils, hydraulic oils, gear oils, crankcase oils and diesel oils. Natural base oils include mineral oils, petroleum oil, paraffinic oils and the ecologically desirable vegetable oils. Typical synthetic oils include pentaerythritol esters, poly-alpha-olefϊns, hydrogenated mineral oils, silicones and silanes. The compositions of the invention may be incorporated in the lubricant in an amount effective to produce the desired antiwear characteristics. An amount from about 0.1 to 10.0 percent will be sufficient for most applications. A preferred range is from about 0.5 to about 3.0 percent by weight of the total lubricant composition. The lubricating compositions may contain other conventional additives depending on the intended use of the lubricant. For example, formulations may contain rust inhibitors such as metal salts of alkylnaphthalenesulfonic acids, demulsifiers, dispersants, detergents and supplemental antioxidants, particularly alkylated diphenylamines. The grease formulations may contain various thickening agents such as, among others, silicate minerals, metal soaps and organic polymers. A preferred fully formulated composition for use as contemplated by this invention may contain one or more of the following additives:

1. Borated and/or non-borated dispersants;

2. Anti-oxidation compounds; Seal swell compositions; Friction modifiers; Extreme pressure/anti-wear agents; Viscosity modifiers; Pour point depressants; Detergents; Antifoamants.

1. Ashless Dispersants. Non-borated ashless dispersants may be incorporated within the final fluid composition in an amount comprising up to 10 weight percent on an oil-free basis. Many types of ashless dispersants listed below are known in the art. Borated ashless dispersants may also be included. (1) "Carboxylic dispersants" which are reaction products of carboxylic acylating agents (acids, anhydrides, esters, etc.) containing at least about 34 and preferably at least about 54 carbon atoms are reacted with nitrogen-containing compounds (such as amines), organic hydroxy compounds (such aliphatic compounds including monohydric and polyhydric alcohols, or aromatic compounds including phenols and naphthols), and/or basic inorganic materials. These reaction products include imide, amide, and ester reaction products of carboxylic acylating agents. Examples of these materials include succinimide dispersants and carboxylic ester dispersants. The carboxylic acylating agents include alkyl succinic acids and anhydridέs wherein the alkyl group is a polybutyl moiety, fatty acids, isoaliphatic acids (e.g. 8-methyl-octadecanoic acid), dimer acids, addition dicarboxylic acids (addition (4+2 and 2+2) products of an unsaturated fatty acid with an unsaturated carboxylic reagent), trimer acids, addition tricarboxylic acids (Empol® 1040, Hystrene® 5460 and Unidyme® 60), and hydrocarbyl substituted carboxylic acylating agents (from olefins and or polyalkenes). In one embodiment, the carboxylic acylating agent is a fatty acid. Fatty acids generally contain from about 8 up to about 30, or from about 12 up to about 24 carbon atoms. Carboxylic acylating agents are taught in U .S. Patent Nos. 2,444,328, 3,219,666 and 4,234,435, the disclosures of which are hereby incorporated by reference. The amine may be a mono- or polyamine. The monoamines generally have at least one hydrocarbyl group containing 1 to about 24 carbon atoms, with from 1 to about 12 carbon atoms. Examples of monoamines include fatty (C8-30) amines, primary ether amines (SURFAM® amines), tertiary-aliphatic primary amines ("Primene"), hydroxyamines (primary, secondary or tertiary alkanol amines), ether N-(hydroxyhydrocarbyl)amines, and hydroxyhydrocarbyl amines (Ethomeens" and "Propomeens"). The polyamines include alkoxylated diamines (Ethoduomeens), fatty diamines ("Duomeens"), alkylenepolyamines (ethylenepolyamines), hydroxy-containing polyamines, polyoxyalkylene polyamines (Jeffamines), condensed polyamines (a condensation reaction between at least one hydroxy compound with at least one polyamine reactant containing at least one primary or secondary amino group), and heterocyclic polyamines. Useful amines include those disclosed in U.S. Pat. No. 4,234,435 (Meinhart) and U.S. Pat. No. 5,230,714 (Steckel) which are incorporated herein by reference.

Examples of these "carboxylic dispersants" are described in British Patent 1,306,529 and in many U.S. Patents including the following: 3,219,666, 3,316,177, 3,340,281, 3,351,552, 3,381,022, 3,433,744, 3,444,170, 3,467,668, 3,501,405, 3,542,680, 3,576,743, 3,632,511, 4,234,435, and Re 26,433 which are incorporated herein by reference for disclosure of dispersants.

(2) "Amine dispersants" are reaction products of relatively high molecular weight aliphatic or alicyclic halides and amines, preferably polyalkylene polyamines. Examples thereof are described for Example, in the following U.S. Patents: 3,275,554, 3,438,757, 3,454,5^5, and 3,565,804 which are incorporated herein by reference for disclosure of dispersants.

(3) "Mannich dispersants" are the reaction products of alkyl phenols in which the alkyl group contains at least about 30 carbon atoms with aldehydes (especially formaldehyde) and amines (especially polyalkylene polyamines). The materials described in the following U.S. Patents are illustrative: 3,036,003, 3,236,770, 3,414,347, 3,448,047, 3,461,172, 3,539,633, 3,586,629, 3,591,598, 3,634,515, 3,725,480, 3,726,882, and 3,980,569 which are incorporated herein by reference for disclosure of dispersants.

(4) Post-treated dispersants are obtained by reacting carboxylic, amine or Mannich dispersants with reagents such as urea, thiourea, carbon disulfide, aldehydes, ketones, carboxylic acids, hydrocarbon-substituted succinic anhydrides, nitriles, epoxides. boron compounds, phosphorus compounds or the like. Exemplary materials of this kind are described in the following U.S. Patents: 3,200,107, 3,282,955, 3.367,943, 3,513,093, 3,639,242, 3,649,659, 3,442,808, 3,455,832, 3,579,450, 3,600,372, 3,702,757, and 3,708,422 which are incorporated herein by reference for disclosure of dispersants.

(5) Polymeric dispersants are interpolymers of oil-solubilizing monomers such as decyl methacrylate, vinyl decyl ether and high molecular weight olefins with monomers containing polar substituents, e.g. aminoalkyl acrylates or acrylamides and poly-(oxyethylene)-substituted acrylates. Examples of polymer dispersants thereof are disclosed in the following U.S. Patents: 3,329,658, 3,449,250, 3,519,656, 3,666,730, 3,687,849, and 3,702,300 which are incorporated herein by reference for disclosure of dispersants.

The above-noted patents are incorporated by reference herein for their disclosures of ashless dispersants.

Borated dispersants are described in U.S. Patents 3,087,936 and 3,254,025 which are incorporated herein by reference for disclosure of borated dispersants.

Also included as possible dispersant additives are those disclosed in U.S. Patents 5, 198,133 and 4,857,214 which are incorporated herein by reference. The dispersants of these patents compare the reaction products of an alkenyl succinimide or succinimide ashless dispersant with a phosphorus ester or with an inorganic phosphorus-containing acid or anhydride and a boron compound. 2. -Antioxidants. Most oleaginous compositions will preferably contain a conventional quantity of one or more antioxidants in order to protect the composition from premature degradation in the presence of air, especially at elevated temperatures. Typical antioxidants include hindered phenolic antioxidants, secondary aromatic amine antioxidants, sulfurized phenolic antioxidants, oil- soluble copper compounds, phosphorus-containing antioxidants, organic sulfides, disulfides, polysulfides and the like.

Illustrative sterically hindered phenolic antioxidants include orthoalkylated phenolic compounds such as 2,6-di-tertbutylphenol, 4-methyl-2,6-di-tertbutylphenol, 2,4,6-tri- tertbutylphenol, 2-tert-butylphenol, 2,6-diisopropylphenol, 2-methyl-6-tert-butylphenol, 2,4- dimethyl-6-tertbutylphenol, 4-(N,N-dimethylaminomethyl)-2,8-di-tertbutylphenol, 4-ethyl-2,6-di- tertbutylphenol, 2-methyl-6-styrylphenol, 2,6-distyryl-4-nonytphenol, and their analogs and homologs. Mixtures of two or more such mononuclear phenolic compounds are also suitable.

Other preferred phenol antioxidants for use in the compositions of this invention are methylene-bridged alkylphenols, and these can be used singly or in combinations with each other, or in combinations with sterically-hindered unbridged phenolic compounds. Illustrative methylene-bridged compounds include 4,4'-methylenebis(6-tert-butyl o-cresol), 4,4'- methylenebis(2-tert-amyl-o-cresol), 2,2'-methylenebis(4-methyl-6-tert-butylphenol), 4,4'- methylenebis (2,6-di-tertbutylphenol), and similar compounds. Particularly preferred are mixtures of methylene-bridged alkylphenols such as are described in U.S. Pat. No. 3,211,652, all disclosure of which is incorporated herein by reference.

Amine antioxidants, especially oil-soluble aromatic secondary amines may also be used in the compositions of this invention. Although aromatic secondary monoamines are preferred, aromatic secondary polyamines are also suitable. Illustrative aromatic secondary monoamines include diphenylamine, alkyl diphenylamines containing 1 or 2 alkyl substituents each having up to about 16 carbon atoms, phenyl-t-naphthylamine, phenyl-β-naphthylamine, alkyl- or aralkylsubstituted phenyl-β-naphthylamine containing one or two alkyl or aralkyl groups each having up to about 16 carbon atoms, alkyl- or aralkylsubstituted phenyl-p-naphthylamine containing one or two alkyl or aralkyl groups each having up to about 16 carbon atoms, and similar compounds.

A preferred type of aromatic amine antioxidant is an alkylated diphenylamine of the general formula

R5-C₆H₄-NH-C₆H₄-R6

wherein R5 is an alkyl group (preferably a branched alkyl group) having 8 to 12 carbon atoms, (more preferably 8 or 9 carbon atoms) and R6 is a hydrogen atom or an alkyl group (preferably a branched alkyl group) having 8 to 12 carbon atoms, (more preferably 8 or 9 carbon atoms). Preferred compounds are available commercially as Naugalube® 438L, 640, and 680 manufactured by Crompton Corporation. Other commercially available aromatic amine antioxidants include Vanlube® SL, DND, NA, 81, 961 and 2005 sold by the R. T. Vanderbilt Company, hie and Irganox® LO6, L57 and L67 manufactured by Ciba-Geigy Corporation.

-Another useful type of antioxidant for preferred inclusion in the compositions of this invention is comprised of one or more liquid, partially sulfurized phenolic compounds such as are prepared by reacting sulfur monochloride with a liquid mixture of phenols—at least about 50 weight percent of which mixture of phenols is composed of one or more reactive, hindered phenols—in proportions to provide from about 0.3 to about 0.7 gram atoms of sulfur monochloride per mole of reactive, hindered phenol so as to produce a liquid product. Typical phenol mixtures useful in making such liquid product compositions include a mixture containing by weight about 75% of 2,6-di-tert-butylphenol, about 10% of 2-tert-butylphenol, about 13% of 2,4,6-tri-tertbutylphenol, and about 2% of 2,4-di-tertbutylphenol. The reaction is exothermic and thus is preferably kept within the range of about 15°C to about 70°C, most preferably between about 40°C to about 60°C. Mixtures of different antioxidants may also be used. One suitable mixture is comprised of a combination of (i) an oil-soluble mixture of at least three different sterically-hindered tertiary butylated monohydric phenols which is in the liquid state at 25°C, (ii) an oil-soluble mixture of at least three different sterically-hindered tertiary butylated methylene-bridged polyphenols, and (iii) at least one bis(4-alkylphenyl) amine wherein the alkyl group is a branched alkyl group having 8 to 12 carbon atoms, the proportions of (i), (ii) and (iii) on a weight basis falling in the range of 3.5 to 5.0 parts of component (i) and 0.9 to 1.2 parts of component (ii) per part by weight of component (iii). The antioxidant discussion above is as put forth in U.S. Pat. No. 5,328,619 which is incorporated herein by reference.

Other useful preferred antioxidants are those included in the disclosure of U.S. Pat. No. 4,031,023 which is herein incorporated by reference. The referenced antioxidants of the '023 patent are then included under the formula:

wherein R is a hydrocarbyl or substituted hydrocarbyl containing up to about 30 carbon atoms and having a valence of m + q; each R' is independently selected from hydrogen and a hydrocarbon-based group of up to about 20 carbon atoms; w and y are independently from 2 to 5; z is from zero to 5; q is from zero to 4 and m is from 1 to 5 with the proviso that m + q is from 1 to 6, have increased resistance to oxidative degradation and anti-wear properties. Anti-oxidants are preferably included in the composition at about 0.1-5 weight percent.

3. Seal Swell Compositions. Compositions which are designed to keep seals pliable are also well known in the art. A preferred seal swell composition is isodecyl sulfolane. The seal swell agent is preferably incorporated into the composition at about 0.1-3 weight percent. Substituted 3-alkoxysulfolanes are disclosed in U.S. Pat. No. 4,029,587 which is incorporated herein by reference.

4. Friction Modifiers. Friction modifiers are also well known to those skilled in the art. A useful list of friction modifiers are included in U.S. Pat. No. 4,792,410 which is incorporated herein by reference. U.S. Patent 5,110,488 discloses metal salts of fatty acids and especially zinc salts and is incorporated herein by reference for said disclosures. Said list of friction modifiers includes:

fatty phosphites fatty acid amides fatty epoxides borated fatty epoxides fatty amines glycerol esters borated glycerol esters alkoxylated fatty amines borated alkoxylated fatty amines metal salts of fatty acids sulfurized olefins fatty imidazolines and mixtures thereof.

The preferred friction modifier is a borated fatty epoxide as previously mentioned as being included for its boron content. Friction modifiers are preferably included in the compositions in the amounts of 0.1-10 weight percent and may be a single -friction modifier or mixtures of two or more.

Friction modifiers also include metal salts of fatty acids. Preferred cations are zinc, magnesium, calcium, and sodium and any other alkali, or alkaline earth metals may be used. The salts may be overbased by including an excess of cations per equivalent of amine. The excess cations are then treated with carbon dioxide to form the carbonate. The metal salts are prepared by reacting a suitable salt with the acid to form the salt, and where appropriate adding carbon dioxide to the reaction mixture to form the carbonate of any cation beyond that needed to form the salt. A preferred -friction modifier is zinc oleate.

5. -Antiwear/Extreme Pressure Agents. (i) dialkyldithiophosphate succinates of the structural formula

wherein R7, R8 and R9 and RIO are independently selected from alkyl groups having 3 to 8 carbon atoms (commercially available as VANLUBE® 7611M, from R. T. Vanderbilt Co., Inc.);

(ii) dithiophosphoric acid esters of carboxylic acid of the formula

wherein Rll and R12 are alkyl having 3 to 8 carbon atoms and R13 is alkyl having 2 to 8 carbon atoms (commercially available as Irgalube® 63 from Ciba Geigy Corp.); and (iii) triphenylphosphorothionates of the formula

(commercially available as Irgalube® TPPT from Ciba Geigy Corp.);

(iv) methylene bis(dialkyldithiocarbamate) wherein the alkyl group contains 4 to 8 carbon atoms (commercially available as VANLUBE ®7723 from R.T. Vanderbilt Co., Inc.).

(v) Phosphorus acid. The lubricating compositions can also preferably include at least one phosphorus acid, phosphorus acid salt, phosphorus acid ester or derivative thereof including sulfur-containing analogs preferably in the amount of 0.002-1.0 weight percent. The phosphorus acids, salts, esters or derivatives thereof include compounds selected from phosphorus acid esters or salts thereof, phosphites, phosphorus- containing amides, phosphorus-containing carboxylic acids or esters, phosphorus- containing ethers and mixtures thereof. hi one embodiment, the phosphorus acid, ester or derivative can be a phosphorus acid, phosphorus acid ester, phosphorus acid salt, or derivative thereof. The phosphorus acids include the phosphoric, phosphonic, phosphinic, and thiophosphoric acids including dithiophosphoric acid as well as the monothiophosphoric, thiophosphinic and thiophosphonic acids.

(vi) Another class of compounds useful to the invention are dithiophosphoric acid esters of carboxylic acid esters. Preferred are alkyl esters having 2 to 8 carbon atoms, as for example 3-[[bis(l-methylethoxy)phosphinothioyl]thio] propionic acid ethyl ester

(vii) A preferred group of phosphorus compounds are dialkyphosphoric acid mono alkyl primary amine salt as represented by the formula

where R14, R15, R16 are hydrogen or alkyl (hydrocarbyl) groups. Compounds of this type are described in U.S. Patent 5,354,484 which is herein incorporated by reference.

Eighty-five percent phosphoric acid is the preferred compound for addition to the fully formulated ATF package and is preferably included at a level of about 0.01- 0.3 weight percent based on the weight of the ATF.

The synergistic amine salts of alkyl phosphates are prepared by known methods, e.g. a method disclosed in U.S. 4,130,494. A suitable mono-or diester of phosphoric acid or their mixtures is neutralized with an amine. When mono-ester is used, two moles of the amine will be required, while the diester will require one mole of the amine. hi any case, the amount of amine required can be controlled by monitoring the neutral point of the reaction where the total acid number is essentially equal to the total base number. Alternately, a neutralizing agent such as ammonia or ethylenediamine can be added to the reaction.

The preferred phosphate esters are aliphatic esters, among others, 2-ethylhexyl, n- octyl, and hexyl mono-or diesters. The amines can be selected from primary or secondary amines. Particularly preferred are tert-alkyl amines having 10 to 24 carbon atoms. These amines are commercially available as for example Primene® 81R manufactured by Rohm and Haas Co.

Zinc salts are preferably added to lubricating compositions in amounts of 0.1-5 weight percent to provide antiwear protection. The zinc salts are preferably added as zinc salts of phosphorodithioic acids or dithiocarbamic acid. Among the preferred compounds are zinc diisooctyl dithiophosphate and zinc dibenzyl dithiophosphate and amyl dithiocarbamic acid. Also included in lubricating compositions in the same weight percent range as the zinc salts to give antiwear/extreme pressure performance is dibutyl hydrogen phosphite (DBPH) and triphenyl monothiophosphate, and the thiocarbamate ester formed by reacting dibutyl amine-carbon disulfide- and the methyl ester of acrylic acid. The thiocarbamate is described in U.S. Pat. No. 4,758,362 and the phosphorus- containing metal salts are described in U.S. Pat. No. 4,466,894. Both patents are incorporated herein by reference.

Antimony or lead salts may also be used for extreme pressure. The preferred salts are of dithiocarbamic acid such as antimony diamyldithiocarbamate.

6. Viscosity Modifiers. Viscosity modifiers (VM) and dispersant viscosity modifiers (DVM) are well known. Examples of VMs and DVMs are polymethacrylates, polyacrylates, polyolefins, styrene-maleic ester copolymers, and similar polymeric substances including homopolymers, copolymers and graft copolymers.

Examples of commercially available VMs, DVMs and their chemical types are listed below. The DVMs are designated by a (D) after their number.

Recent summaries of viscosity modifiers can be found in U.S. patents 5,157,088, 5,256,752 and 5,395,539 which are herein incorporated by reference for disclosure pertinent to this invention. The VMs and/or DVMs preferably are incorporated into the fully-formulated compositions at a level of up to 10% by weight. 7. Pour Point Depressants. These components are particularly useful to improve low temperature qualities of a lubricating oil. A preferred pour point depressant is an alkylnaphthalene. Pour point depressants are disclosed in U.S. Pat. Nos. 4,880,553 and 4,753,745, which are incorporated herein by reference. PPDs are commonly applied to lubricating compositions to reduce viscosity measured at low temperatures and low rates of shear. The pour point depressants are preferably used in the range of 0.1-5 weight percent. Examples of tests used to access low temperature low shear-rate rheology of lubricating fluids include ASTM D97 (pour point), ASTM D2983 (Brookfield viscosity), D4684 (Mini-rotary Viscometer) and D5133 (Scanning Brookfield). Examples of commercially available pour point depressants and their chemical types are:

8. Detergents. Lubricating compositions in many cases also preferably include detergents. Detergents as used herein are preferably metal salts of organic acids. The organic acid portion of the detergent is preferably a sulphonate, carboxylate, phenate, salicylate. The metal portion of the detergent is preferably an alkali or alkaline earth metal. Preferred metals are sodium, calcium, potassium and magnesium. Preferably, the detergents are overbased, meaning that there is a stoichiometric excess of metal over that needed to form the neutral metal salt. Preferred overbased organic salts are the sulfonate salts having a substantially oleophilic character and which are formed from organic materials. Organic sulfonates are well known materials in the lubricant and detergent arts. The sulfonate compound should preferably contain on average from about 10 to about 40 carbon atoms, more preferably from about 12 to about 36 carbon atoms and most preferably from about 14 to about 32 carbon atoms on average. Similarly, the phenates, oxylates and carboxylates preferably have a substantially oleophilic character.

While the present invention allows for the carbon atoms to be either aromatic or in paraffinic configuration, it is highly preferred that alkylated aromatics be employed. While naphthalene based materials may be employed, the aromatic of choice is the benzene moiety.

The most preferred component is thus an overbased monosulfonated alkylated benzene, and is preferably the monoalkylated benzene. Preferably, alkyl benzene fractions are obtained from still bottom sources and are mono- or di-alkylated. It is believed, in the present invention, that the mono-alkylated aromatics are superior to the dialkylated aromatics in overall properties.

It is preferred that a mixture of mono-alkylated aromatics (benzene) be utilized to obtain the mono-alkylated salt (benzene sulfonate) in the present invention. The mixtures wherein a substantial portion of the composition contains polymers of propylene as the source of the alkyl groups assist in the solubility of the salt. The use of monofunctional (e.g., mono-sulfonated) materials avoids crosslinking of the molecules with less precipitation of the salt from the lubricant.

It is preferred that the salt be "overbased". By overbasing, it is meant that a stoichiometric excess of the metal be present over that required to neutralize the anion of the salt. The excess metal from overbasing has the effect of neutralizing acids which may build up in the lubricant. A second advantage is that the overbased salt increases the dynamic coefficient of friction. Preferably, the excess metal will be present over that which is required to neutralize the acids at about in the ratio of up to about 30:1, preferably 5:1 to 18:1 on an equivalent basis. The amount of the overbased salt utilized in the composition is preferably from about 0.1 to about 10 weight percents on an oil free basis. The overbased salt is usually made up in about 50% oil with a TBN range of 10-600 on an oil free basis. Borated and non-borated overbased detergents are described in U.S Patents 5,403,501 and 4,792,410 which are herein incorporated by reference for disclosure pertinent hereto.

9. Antifoamant. Antifoaming agents are well-known in the art as silicone or fluorosilicone compositions. Such antifoam agents are available from Dow Corning Chemical Corporation and Union Carbide Corporation. A preferred fluorosilicone antifoam product is Dow FS-1265. Preferred silicone antifoam products are Dow Corning DC-200 and Union Carbide UC-L45. Other antifoam agents which may be included in the composition either alone or in admixture is a polyacrylate antifoamer available from Monsanto Polymer Products Co. of Nitro, West Virginia known as PC- 1244 or Mobilad® C402 from ExxonMobil Chemical Corp. Also, a siloxane polyether copolymer antifoamer available from OSI Specialties, Inc. of Farmington Hills, Michigan and may also be included. One such material is sold as SILWET-L-7220. The antifoam products are preferably included in the compositions of this invention at a level of 5 to 80 parts per million with the active ingredient being on an oil-free basis.

EXAMPLES The following examples are given for the purpose of illustrating the invention and are not intended in any way to limit the invention. All percentages and parts are based on weight unless otherwise indicated.

EXAMPLE 1

N-N,-Dibutyldithiocarbamyl-2,3-propanediol From Glycidol (reference 491-150) Dibutylamine (49.9g, 0.386 mole) and isopropanol (91.4g) ) were charged to a 3 neck reaction flask equipped with strirrer and reflux condensor. An ice water bath was placed under the reaction. Carbon disulfide (32.0g , 0.420 mole) was added slowly while keeping the reaction at or slightly below 40° C (reaction exothermic). Additional isopropanol (5.9g) was charged. After stirring for approximately lh, glycidol (29.7g, 96% active, 0.385 mole) was charged cautiously (exothermic, temperature rose to 47C with a slow addition). Additional isopropanol (23 g) was charged. The reaction was held overnight (no stirring) and then the isopropanol and excess carbon disulfide were distilled off under vacuum (20 m-mHg⁰) to afford the product. From 3-chloro-l,2-propanediol (reference 508-27) Dibutylamine (68. lg, 0.527 mole), isopropanol (123. lg) , sodium hydroxide (20.4g in 21.3g water, 0.5mole), sodium carbonate (6.7g, 0.0632 mole) , and sodium sulfite (0.4g) were charged to a reaction flask. Carbon disulfide (43. Og, 0.565 mole) was slowly added (exothermic) while the reaction was kept at 40°C maximum temperature. After reaction of all carbon disulfide was complete, 3-chloro-l,2,-propandiol (58.3g, 0.527mole) was cautiously added. Additional isopropanol (41.9g) was added. Product was heated to 80°C for approximately 4 hours. The product was filtered to remove sodium chloride and the product was isolated by rotary evaporation of the solvent to yield 131.9g (89.6% yield) of the final product.

EXAMPLE 2

N-N,-Dipentyl(mixed branched isomer)dithiocarbamyl-2,3-propanediol

From Glycidol (reference 491-144)

Diamylamine (51.2g , 0.325mole) and isopropanol (91g) were charged to a 3 neck reaction flask equipped with strirrer and reflux condensor. An ice water bath was placed under the reaction. Carbon disulfide (26.9g, 0.353 mole) was added slowly while keeping the reaction at or slightly below 40° C (reaction exothermic). Additional isopropanol (2.8g) was charged. After stirring for approximately lh, glycidol (25.3g, 96% active, 0.328 mole) was charged cautiously (exothermic, temperature rose to 47C with a slow addition). Additional isopropanol (5 g) was charged. The reaction was held overnight (no stirring) and then the isopropanol and excess carbon disulfide were distilled off under vacuum (20 mmHg⁰) to afford the product. Total base number (TBN) of the final product was lmgKOH/g indicating a diamylamine level of less than 0.29%). This is consistent with a high conversion. From 3-chloro-l,2-propanediol (ref. 491-177 ) The product was prepared in a similar fashion to example 1 utilizing diamylamine as the starting amine.

EXAMPLE 3

N,N-di(2-ethylhexyl)dithiocarbamyl-2,3-propanediol From Glycidol (reference 480-212) Di-(2-ethylhexyl)amine (80.5g, 0.333) and isopropanol (91.0g) were charged to a 3 neck flask. Carbon disulfide (27.6g, 0.363 mole) was charged slowly (exothermic) while maintaining the reaction at 35°C or less. The reaction was stirred for 35 minutes at ca. 35°C and then the reaction was cooled to 15 °C with an ice bath. Glycidol (25.7g, 0.333mole) was added dropwise with cooling to maintain the reaction below 35°C (exothermic). The reaction was stirred for 45 minutes and the isopropanol (as well as any unreacted carbon disulfide) were removed by distilling (90°C @20mmHg^o) which afforded the final product From chloro-2,3-propandioI (ref. 491-189) The product was prepared in a similar fashion to Example 1 utilizing di-(2- ethylhexyl)amine as the starting amine.

EXAMPLE 4

N-(2-ethylhexyl)-N-(tridecyl) dithiocarbamyl -2,3-p-ropaιιediol (ref.480-214) The reaction was run as Example 3 with the molar substitution of tridecyl(2- ethylhexyl)amine for the secondary amine.

EXAMPLE 5

N,N-ditridecyl dithiocarbamyl -2,3-propanediol (ref.480-213) The reaction was run as Example 3 with the molar substitution of ditridecylamine for the secondary amine.

EXAMPLE 6

Borated N-N,-DibutyIdithiocarbamyI-2,3-propanediol (ref.480-218) Example 1 (18.5g) and boric acid (4.12g) were charged and mixed in a round bottom flask. A 20mm Hg° vacuum was applied at 27°C on the rotary evaporator. The reaction was heated to 90C for 4 hours, filtered hot to afford the final product. The boron content was 3.54% in theory.

EXAMPLE 7

Borated N,N-dipentyl(mixed branched isonιer)dithiocarbamyl-2,3-propanediol (480-219) Example 2 (20.50g), Uninap SD-100 oil (16.53g), and boric acid (4.12g). The same procedure as Example 6 was used. The boron content was 1.94% in theory.

EXAMPLE 8

Borated N,N-di-(2-ethylhexyl)dithiocarbamyl-2,3-propanediol (ref.480-215) Example 3 was borated as in Example 7 to afford a product with 1.47% boron in theory.

EXAMPLE 9

Borated N-(2-ethylhexyl)-N-(tridecyl) dithiocarbamyl -2,3-propanediol (ref.480-217) Example 4 was borated as in Example 7 to afford a product with 1.32% boron in theory.

EXAMPLE 10

Borated N,N-ditridecyl dithiocarbamyl -2,3-propanediol (ref.480-216) Example 5 was borated as in Example 7 to afford a product with 1.07% boron in theory.

EXAMPLE 11 A laboratory test was conducted by using the original Falex machine to simulate the valve train wear of an automobile engine. The V-blocks and pin were washed in mineral spirits with an ultrasonic cleaner, rinsed with acetone, air dried and weighed. The test sample (60 g) was placed into the oil cup. The motor was switched on and the loading arm was placed on the ratchet wheel. Upon reaching the reference load of 227 kg, the ratchet wheel was disengaged and the load was maintained constant for 3.5 hours. Thereafter, the motor was switched off. The V- blocks and pin were washed, dried and weighed. The weight loss, a measure of wear, was recorded and compiled in Table I. The base oil was a hydrofinished naphthenic oil (ISO VG 22 manufactured by Sun Refining and Marketing Co.).

The results compiled in Table II indicate that the dithiocarbamate diols provide excellent antiwear and the borated analogs provide even further improvement towards inhibition of wear.

Soluble test: P is in Exxon 150SN, N is in Uninap 100SD. G=good, cl= cloudy, sh=slight haze, h= hazy

*Test stopped excessive wear, could not maintain load **Brass shear pin broke ***Steel test pin broke EXAMPLE 12 A thin film oxygen uptake test was conducted essentially according to the method described by Chia-Soon Ju et al, J. Am. Soc. Lubricating Eng., 40, 2, 75-83, 1984. The oxidation induction time of the lubricant was measured under conditions which simulate the high temperature oxidation processes in automotive engines by modified rotary bomb oxidation test method ASTM D-2272. The test was conducted with 1.5 gram samples of hydrofinished naphthenic oil, ISO VG 22. The composition of the invention described in Example 1 and, for comparison, the individual components, were added to the oil in the amount indicated in Table in. The test was conducted at 160°C and initial oxygen pressure of 620.6 kPa (90 psi). A "pass" oil has a high induction time, while a "fail" oil has a low induction time. The compositions of the invention display good antioxidative effect as demonstrated by the data compiled in Table in.

The above embodiments have shown various aspects of the present invention. Other variations will be evident to those skilled in the art and such modifications are intended to be within the scope of the invention as defined by the appended claims.

Claims

1. A dithiocarbamate compound of formula (I) :

wherein Rl and R2 are the same or different and represent alkyl groups, branched or straight chain, having 1 to 13 carbon atoms, R3 and R4 are the same or different and represent hydrogen, boric acid ester residue or mixtures thereof. ^l

2. The dithiocarbamate compound of claim 1, wherein R3 and R4 are both hydrogen and Rl and R2 are the same or different and represent alkyl groups, branched or straight chain, having 1 to 7 carbon atoms.

3. The dithiocarbamate compound of claim 2, wherein R3 and R4 are both hydrogen and Rl and R2 are the same or different and represent alkyl groups, branched or straight chain, having 5 to 6 carbon atoms.

4. The dithiocarbamate compound of claim 3, wherein R3 and R4 are both hydrogen and Rl and R2 are the same and are n-butyl or n-pentyl.

5. A dithiocarbamate compound formed by the reaction of: (a) a compound of formula (I):

wherein Rl and R2 are the same or different and represent alkyl groups, branched or straight chain, having 1 to 13 carbon atoms and R3 and R4 are hydrogen; and (b) boric acid.

6. The dithiocarbamate compound of claim 5, wherein Rl and R2 are the same or different and represent alkyl groups, branched or straight chain, having 1 to 7 carbon atoms.

7. The dithiocarbamate compound of claim 6, wherein Rl and R2 are the same or different and represent alkyl groups, branched or straight chain, having 5 to 6 carbon atoms.

8. The dithiocarbamate compound of claim 7, wherein Rl and R2 are the same and are n- butyl or n-pentyl.

9. A dithiocarbmate compound of formula (II):

wherein Rl and R2 are the same or different and represent alkyl groups, branched or straight chain, having 1 to 13 carbon atoms.

10. The dithiocarbamate compound of claim 9, wherein Rl and R2 are the same or different and represent alkyl groups, branched or straight chain, having 1 to 7 carbon atoms.

11. The dithiocarbamate compound of claim 10, wherein Rl and R2 are the same or different and represent alkyl groups, branched or straight chain, having 5 to 6 carbon atoms.

12. The dithiocarbamate compound of claim 11, wherein Rl and R2 are the same and are n- butyl or n-pentyl.

13. A dithiocarbamate compound of formula (III) :

14. The dithiocarbamate compound of claim 13, wherein Rl and R2 are the same or different and represent alkyl groups, branched or straight chain, having 1 to 7 carbon atoms.

15. The dithiocarbamate of claim 14, wherein Rl and R2 are the same or different and represent alkyl groups, branched or straight chain, having 5 to 6 carbon atoms.

16. The dithiocarbamate of claim 15, wherein Rl and R2 are the same and are n-butyl or n- pentyl.

17. A method of making the compound of claim 9 or 13 which comprises of reacting a compound of formula (I):

wherein Rl and R2 are the same or different and represent alkyl groups, branched or straight chain, having 1 to 13 carbon atoms, and R3 and R4 are hydrogen, with boric acid wherein, the ratio of boric acid to the compound of formula (I) is about 0.25:1 to about 2.0:1.

18. The method of claim 17, wherein the ratio of boric acid to the compound of formula (I) is about 0.75:1 to about 1.25:1.

19. The method of claim 18, wherein the ratio of boric acid to the compound of formula (I) is about 1.0: 1.

20. A lubricant composition comprising: (a) a base oil in an amount from about 90.0% to about 99.9% by weight based on the total weight of the lubricant composition; and (b) a dithiocarbamate compound of formula (I):

in an amount from 0.1 to 10.0% by weight based on the total weight of the lubricant composition, wherein, Rl and R2 are the same or different and represent alkyl groups, branched or straight chain, having 1 to 13 carbon atoms, R3 and R4 are the same or different and represent hydrogen, boric acid ester residue or mixtures thereof.

21. The lubricant composition of claim 20, wherein Rl and R2 are the same or different and represent alkyl groups, branched or straight chain, having 1 to 7 carbon atoms.

22. The lubricant composition of claim 21, wherein Rl and R2 are the same or different and represent alkyl groups, branched or straight chain, having 5 to 6 carbon atoms.

23. The lubricant composition of claim 22, wherein Rl and R2 are the same and are n-butyl or n-pentyl.

24. A lubricant composition comprising: (a) a base oil in an amount from about 90.0% to about 99.9% by weight based on the total weight of the lubricant composition; and (b) the dithiocarbamate compound formed by the reaction of a compound of formula (I):

wherein Rl and R2 are the same or different and represent alkyl groups, branched or straight chain, having 1 to 13 carbon atoms and R3 and R4 are hydrogen; and boric acid, in an amount from 0.1 to 10.0% by weight based on the total weight of the _/lubricant composition.

25. The lubricant composition of claim 24, wherein Rl and R2 are the same or different and represent alkyl groups, branched or straight chain, having 1 to 7 carbon atoms.

26. The lubricant composition of claim 25, wherein Rl and R2 are the same or different and represent alkyl groups, branched or straight chain, having 5 to 6 carbon atoms.

27. The lubricant composition of claim 26, wherein Rl and R2 are the same and are n-butyl or n-pentyl.

28. A lubricant composition comprising: (a) a base oil in an amount from about 90.0% to about 99.9% by weight based on the total weight of the lubricant composition; and (b) a dithiocarbamate compound selected from the group consisting of a compound of formula (II):

a compound of formula (JU):

and mixtures thereof, in an amount from 0.1 to 10.0% by weight based on the total weight of the lubricant composition, wherein, Rl and R2 are the same or different and represent alkyl groups, branched or straight chain, having 1 to 13 carbon atoms.

29. The lubricant composition of claim 28, wherein Rl and R2 are the same or different and represent alkyl groups, branched or straight chain, having 1 to 7 carbon atoms.

30. The lubricant composition of claim 29, wherein Rl and R2 are the same or different and represent alkyl groups, branched or straight chain, having 5 to 6 carbon atoms.

31. The lubricant composition of claim 30, wherein Rl and R2 are the same and are n-butyl or n-pentyl.

32. The lubricant composition of any one of claims 20-31 which further comprises one or more additives selected from the group consisting of: (1) Borated dispersants; (2) Non-borated dispersants; (3) Anti-oxidation compounds; (4) Seal swell compositions; (5) Friction modifiers; (6) Extreme pressure/anti-wear agents; (7) Pour point depressants; (8) Detergents; (9) Antifoamants; and (10) mixtures thereof.